In known solenoid assemblies having encapsulated coils, a major problem encountered is providing the encapsulation around the coil so that moisture or other contaminants cannot reach the windings of the coil. Contaminants being exposed to the windings of the coil normally causes premature failure of the coil assembly. Failure of the coil assembly may cause a machine to be shut down until the coil assembly is replaced. Such shut down can be very costly to the owner of the machine. Various attempts have been made in the past to provide positive sealing of the over-molded material relative to the coil. Special emphasis has been placed on sealing between the over-molded material and the electrical leads extending from the coil to the exterior of the coil assembly. Likewise, various changes has been made to the over-molded material in order to help ensure that it bonds to the bobbin of the coil. This has proven to be helpful but many times creates other problems during the molding process. Most of the coil bobbins made in the past had square corners that proved to hamper the ability to ensure adequate sealing at the corners during molding of the over-molded material around the coil. One attempt that has proven to be helpful is to provide a tapered flange for sealing as opposed to a square cornered flange. The tapered sealing flange provides a thin portion at the edge of the taper that melts back during the molding process. A major problem with this type of bobbin is that the sharp, thin edge of the taper can easily be damaged during production and handling of the bobbin prior to the molding process. Any damage or crushing (large or small dent or impression on the sharp edge) of any part of the sharp, thin edge prior to the molding process provides a potential leakage path since the crushed or damaged portion may not effectively melt back during the molding process.
The present invention is directed to overcoming one or more of the problems as set forth above.